We propose to develop an isolated breeding facility for marmosets and tamarins in semi-outdoor conditions. The purpose of the facility is to enable us to study improved methods of husbandry for small family units of 3 species of Callitrichids. We will study the effect of territorial security, privacy, and visual screening as behavioral aspects of our program. We will study diet acceptability, multiple feeding stations, and feed station location as nutritional aspects of our program. We will study family group housing and dispersed families of like species vs. close association of like species as social aspects of our program. Our plan is to concentrate our efforts on the propagation of Saguinus oedipus oedipus as a first priority since this is nearly an endangered species which has valuable applications in biomedical research. We will use Callithrix jacchus jacchus, a species with large potential in research, and Saguinus fuscicollis ssp, a species important to our own research as buffers for species dispersal within the breeding facility. At the same time we will test the above methods on the latter 2 species.